To investigate the influence of gas pressure on the process of gliding arc discharge, the spectral characteristics of gliding arc discharge were studied on a high-pressure discharge experimental platform. The excited state substances in gliding arc discharge are diagnosed by emission spectroscopy,and the electron density, vibration temperature and rotation temperature of gliding arc discharge under different gas pressures are calculated. The emission lines of the second positive system of nitrogen N2(C3Πu→B3Πg) and the first negative system of nitrogen N+2(B2Σ+u→X2Σ+g) are observed in the emission spectra of the gliding arc discharge. With the increase of gas pressure, the emission intensity of the emission line of the second positive system of nitrogen increases, whereas the emission intensity of the first negative system of nitrogen changes slightly. The Stark broadening method calculates the electron density in gliding arc discharge. It is found that the electron density is 1023 orders of magnitude, and the electron density increases linearly with the increase of gas pressure. The vibration temperature of sliding arc discharge is calculated using the Boltzmann diagram method for the five spectral lines of the second positive system of nitrogen molecules. The change of vibration temperature with gas pressure is not monotone. The range of vibration temperature changes is small before 0.3 MPa and increases rapidly after the gas pressure exceeds 0.3 MPa. The rotational temperature of the discharge from the gliding arc was calculated by fitting the emission lines at 390~391.6 nm in the first negative nitrogen molecules system. The rotational temperature changed significantly with the increase of gas pressure before 0.24 MPa, and the addition of rotational temperature decreased when the gas pressure exceeded 0.24 MPa.